During designing and manufacturing procedure of a low temperature poly-silicon panel, if a film surface on a side of an array substrate is irregular, poor alignment of liquid crystal of a liquid crystal display device would occur.
In the prior art, a thickness of an insulation layer between a common electrode and a source/drain is usually increased so as to flatten the film surface and improve the alignment performance of liquid crystal. However, since the insulation layer has a relative larger thickness compared with other film layers, it is necessary to arrange a via hole in the insulation layer when the source/drain of a thin film transistor breakover needs to be connected with a pixel electrode. Because the insulation layer is made from high molecular material and comprises relatively deep via holes, in the preparation procedure, it will be easy for the insulation layer to be separated from a film layer which is originally in contact with the insulation layer. As a result, the pixel electrode and the source or the drain would have a poor contact or even be disconnected from each other, thereby affecting normal display of the liquid crystal display device. In this case, the thickness of the insulation layer should be reduced so as to lower the risk of poor contact. However, if the thickness of the insulation layer is reduced, a flatness of the insulation layer would be affected, which would causes poor alignment of the liquid crystal.
In this case, a new array substrate that can improve the contact between the pixel electrode and the source/drain without affecting the flatness of the insulation layer is needed.